Current stationary imaging devices used in Nuclear Medicine have serious limitations on resolution and sensitivity at count rates above 100K counts per second (CPS). This count rate is likely to be encountered during studies of the cardiovascular system and in investigations of regional blood flow. Development of new isotopes which give lower dose will permit higher count rates providing the instrumentation can handle it. It is proposed to design, construct and test a high pressure Xenon filled multiwire proportional chamber which will perform at count rates twenty times higher than existing devices with better spatial resolution and better energy resolution. The lower intrinsic sensitivity of the chamber will be compensated for by its low resolving time which will allow it to process more detected photons at high count rates. This chamber will be interfaced to an existing small digital computer which is installed in a Nuclear Medicine laboratory for performance testing and clinical verification.